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Displaying posts with tag: MySQL (reset)
MySQL, Percona, MariaDB long running processes clean up one liner

There are tools like pt-kill from the percona tool kit that may print/kill the long running transactions at MariaDB, MySQL or at Percona data instances, but a lot of backup scripts are just some simple bash lines.
So checking for long running transactions before the backup to be executed seems to be a step that is missed a lot.

Here is one line that might be just added in every bash script before the backup to be executed
Variant 1. Just log all the processlist entries and calculate which ones were running longer than TIMELIMIT:

$ export TIMELIMIT=70 && echo "$(date) : check for long runnig queries start:" >> /tmp/processlist.list.to.kill && mysql -BN -e 'show processlist;' | tee -a /tmp/processlist.list.to.kill | awk -vlongtime=${TIMELIMIT} '($6>longtime){print "kill "$1";"}' | tee -a /tmp/processlist.list.to.kill

Variant 2: Log all the processlist, calculate the calculate which processes are …

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Optimizer hints in MySQL 5.7.7 – The missed manual

In version MySQL 5.7.7 Oracle presented a new promising feature: optimizer hints. However it did not publish any documentation about the hints. The only note which I found in the user manual about the hints is:

  • It is now possible to provide hints to the optimizer by including /*+ ... */ comments following the SELECT, INSERT, REPLACE, …
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SSL/TLS in 5.6 and 5.5 – oCERT Advisory

Today, oCERT published advisory 2015-003 describing a TLS vulnerability in MySQL and derivative products.  The content isn’t exactly news – it is documented legacy behavior and the subject of an earlier blog post describing how MySQL Server 5.7 solves the problem.  That said, the efforts of Duo Security are certainly appreciated and welcomed – it provides a meaningful context to discuss how to properly harden existing MySQL 5.5 and 5.6 deployments, as well as frame a discussion on potential changes in these versions to increase security.

Vulnerability

The vulnerability described in the advisory relies on the legacy behavior of the client …

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Percona Acquires Tokutek : My Thoughts #2 : TokuMX and TokuMXse

A few days ago I wrote up my thoughts about the Percona acquisition of Tokutek with respect to TokuDB. In this blog I'm going to do the same for TokuMX and TokuMXse. And in a few days I'll wrap up this trilogy by sharing my thoughts about Fractal Tree Indexes.

Again, when I'm writing up something that I was very involved with in the past I think it's important to disclose that I worked at Tokutek for 3.5 years (08/2011 - 01/2015) as VP/Engineering and I do not have any equity in Tokutek or Percona.

Since much of the MySQL crowd might be hearing about Tokutek's "other products" for the first time I'll provide a little history of both of the products before I dive in deeper.

TokuMX is a fork of MongoDB …

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Generated (Virtual) Columns in MySQL 5.7 (labs)

About 2 weeks ago Oracle published the MySQL 5.7.7-labs-json version which includes a very interesting feature called “Generated columns” (also know as Virtual or Computed columns). MariaDB has a similar feature as well: Virtual (Computed) Columns.

The idea is very simple: if we store a column

`FlightDate` date

in our table we may want to filter or group by year(FlightDate), month(FlightDate) or even dayofweek(FlightDate). The “brute-force” approach: use the above Date and Time MySQL functions in the query; however it will prevent MySQL from using an index (see below). Generated columns will allow you to declare a “Virtual”, non-stored column …

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MySQL 5.7 — Native Systemd Support

Introduction

Systemd is a management and configuration platform available in all major Linux distributions. It provides infrastructure for service start, stop, restart and several other novel functionalities to manage services. Systemd replaces SysV and upstart initialization systems and is the default init system in most modern Linux distributions including Red Hat Enterprise Linux, Oracle Linux, Debian, Ubuntu, Fedora, SLES and openSUSE.

Preliminary support for systemd was introduced in earlier versions of MySQL. However, it had the following limitations and disadvantages:

  1. Use of ping tricks to check whether mysqld is ready to serve client connections.
  2. Though systemd had superior process control for automatic restarts, mysqld_safe was still used to identify abnormal mysqld termination and do automatic restarts.
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How-to extract from mysqldump | mysql-dump-splitter recipes

This post will answer how to extract database, tables etc from mysqldumpsplitter utility.

The post How-to extract from mysqldump | mysql-dump-splitter recipes first appeared on Change Is Inevitable.

Test your knowledge: Percona XtraDB Cluster (PXC) quiz

I often talk with people who are very interested in the features of Percona XtraDB Cluster (PXC) such as synchronous and parallel replication, multi-node writing and high availability. However some get confused when operating a real PXC cluster because they do not fully realize the implications of these features. So here is a fun way to test your PXC knowledge: try to solve these 12 questions related to PXC! (you will find the answers at the end of the post.)

Workload

1. With Galera 3.x, support for MyISAM is experimental. When can we expect to have full MyISAM support?
a. This will never happen as Galera is designed for transactional storage engines.
b. This is planned for Galera 4.0.

2. Why aren’t all workloads a good fit for PXC?
a. Execution plans can change compared to a regular MySQL server, so performance is sometimes not as good as with a regular MySQL server.
b. Large …

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Strip your TEXT Field

TEXT fields are a nightmare. For you and for your server. It is slow to retrieve, and if you are doing searches on it, be prepared, things are going to get bumpy.

If you use MySQL with a MyISAM engine, this may not be an issue for you, you can create a FULLTEXT index, your only problem is if you want to add a new column, an alter table can take forever, since MySQL creates a new table and copies the old data to the new table. For those who uses MySQL with an InnoDB engine, prepare because, you’ll have more issues. Indexes can’t be FULLTEXT and if you do need an index you must inform the length of it. It defeats the purpose of you doing the search in that field.

The observation above is only true for MySQL 5.5 or below, since version 5.6 MySQL does support FULLTEXT indexes on InnoDB – thanks Davey …

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Percona Acquires Tokutek : My Thoughts #1 : TokuDB

Two weeks ago Percona announced it's acquisition of Tokutek (April 14, 2015). The analyst coverage was a bit fluffy for my liking, but I decided to give it some time and see if anything "meaty" would come along, and ... it hasn't. The sheer number of tweets on Twitter was impressive, which makes me hopeful that the acquisition raised awareness to the Tokutek technologies and that the Tokutek products have a found a good home

I've been thinking a lot about the future of the Tokutek technologies over these same two weeks and want to share them publicly. I'm going to cover TokuDB in this blog post, TokuMX in a few days, and finally Fractal Tree Indexes a few days later. [Full disclosure: I worked at Tokutek for 3.5 years (08/2011 - 01/2015) as VP/Engineering and I do not have any equity in Tokutek or Percona]

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